I know of the RV you refer to that "broke" the canopy. Actually the canopy didn't break but the frame somehow torqued and came out of alignment and we're not sure it was as a result of doing snaps. Personally, I have snapped my RV-8 hundreds of times with no ill effects. I stay well below maneuvering speed (122 knots) and find my sweet spot for snap entry is 100-110 knots. I have never seen more than 3.5 Gs during snaps.
BTW, for easy acro you won't even need inverted fuel. You might look into a half Raven system to catch your vented oil though. That will work better than any air/oil separator on the market.
Please excuse my absence from this thread. I just got back yesterday afternoon form a 10 day trip out west in the Bonanza with the family. It was hoot!
Yes, it is I, Jerry Esquenazi, that had the canopy issues. Many people have snapped their RVs without any issues. I unfortunately, have had problems with my canopy which I believe was indeed caused by snap rolls. Most people are concerned about the tail. Who knew the canopy would be a problem?!
In Jan 2019, after being down for three weeks repairing a fuel tank leak, I was out doing snap rolls and rolling turns. I had attempted them before, but this was my first real practice with both maneuvers. I had done half a dozen of each and immediately following my last snap roll, I heard a loud bang. The canopy had cracked. It was 12" crack on the right side starting from one of the screw holes a few inches aft of my seat back. I was fortunate in that when I built my plane, I had assembled the canopy with screws instead of blind rivets. It made it much easier to replace the plexiglass without harming the skirt and the intricate paint job.
Did it crack because of the snap roll, some prior maneuver, or pure dumb luck? I don't know. At the time, my canopy was already 12 years in service, 15-16 years old since I purchased the finish kit. I already had a few hairline fractures around some of the screw holes, and it was quite cold for Georgia.
The airplane was down for 6 weeks while I replaced the plexiglass. In late Mar 2019 I went to my first Intermediate contest cold turkey. The snap rolls and lack of practice proved to be my nemesis. I then went to SNF and upon my return I set out to perfect my snap rolls. During practice, after about a dozen snap rolls to the left, my canopy popped open on the right side near the canopy bow. I had been seeing a glint of light from the corner of my eye to the right on every snap roll, but I thought it was just a reflection. In hindsight, I realize now that the canopy was opening slightly on the right every time I snapped. I suspect this was due to either air loads and torsion on the canopy or torsion on the fuselage. I purposely left the canopy untouched until after shut down. The latch was latched, the rollers in their tracks, and the aft center pin of the frame was fully seated in the block. Yet, the very aft end of the skirt where it rides over the center track, was pushed over about an inch to the left. I asked my coach to push on the canopy and it snapped back into place mostly. Something was deformed.
I suspect the canopy frame was deformed when it opened. Some have asked about my fuselage. I haven't taken any measurements, but there are no wrinkles in the skin, there aren't any popped rivets, the airplane flies straight and true, and my eyeball says it's straight. With that, I have had the canopy apart three times in the last year in an attempt to fix the issues. I've got it very close now, but it's not perfect like it once was.
I don't think it was a coincidence that I experienced a second canopy problem while doing snap rolls. Because of this I decided last year that I was no longer going to compete with my RV-8 since I don't feel comfortable doing snap rolls with it. Sure I can go back to flying Sportsman and avoid snaps. But now that I've tasted the challenges of Intermediate and hope to one day compete in Advanced, I've decided to focus my energy on getting the right airplane for the task. Some of my friends joked that I should try some snaps to the right to bend the canopy back into shape!
For the record I was doing my snap rolls at 90 kts and once I picked up the speed to 100 kts, never exceeding 3 g during the maneuvers. It sure did snap a lot nicer at 100!
I spoke with someone recently at a fly-in that had been receiving instruction from a highly experienced, nationally recognized, aerobatic instructor in their RV-8. Well into the course, they began doing snap rolls and the instructor sitting in the back seat was surprised to see movement, flexing, and deformation of the canopy during the maneuver. His canopy later cracked in an eerily similar location as mine.
I know that both Ron and Bill have had canopy issues with the cause undetermined. In Ron's case, the canopy actually cracked after a flight while sitting on the ramp!
I now have my canopy as good as it's going to get. I'm still enjoying aerobatics and have been watching the canopy carefully. I can do all of the Sportsman maneuvers including spins with confidence in the canopy. I'm not seeing any movement or flexing. That said, I hope the next snap roll I do will be in an Extra 300.